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Re:How do McDonald's debit card payments get processed in un... by eduardordm on Wednesday December 04, 2013 @08:29AM (#6846693)
Hi Marco, I own a credit card company/bank/gateway and I can answer that:

They are using a small protocol (XML or plain ISO8583) over a somewhat fast connection (X.25, GPRS, 3G or the store's internet - ADSL, etc). Connections are always kept alive for a certain amount of time.

The bank side of processing is very simple and shouldn't take long. Keep in mind that the data used to authorize a transaction is minimal. After the authorization is given, the bank will process the actual payment, which is a two-step job with the first step being executed minutes after the purchase and the second one usually at night.

I wouldn't recommend you digging too much into banking standards without a specific purpose. There are just so many and almost no one strictly follows them. This is a good start: http://www.aba.com/Pages/default.aspx and https://www.pcisecuritystandards.org/

Re:How do McDonald's debit card payments get processed in un... by ceoloide on Thursday December 05, 2013 @04:27PM (#6857381)
Thank you very much Eduardo! You are the first that gives me a possible technical explanation.

McDonald's are in most cases wired with ADSL or faster connection, since they serve free wifi in the store. I would guess they use the same connection for the POS.

My two guesses were:

1) Fast connection with fast standard and maybe custom software to keep the channel open. 2) Pre-authorization, given the small sums paid and the low probability of frauds.

I do also think that McDonald's might have a specific agreement with a gateway or a bank. They use Ingenico's POS, so I ruled out custom hardware.

I will update the thread if I find anything interesting! Thank you again!

Marco